Nonlinear Burgers Type Equation for Acoustic Waves in the Ray Approximation in a Moving Atmosphere (Theory, Experiment)

The derivation of a nonlinear Burgers-type equation for acoustic waves within the ray approximation for an inhomogeneous moving dissipative atmosphere is presented. The equation is applied to investigate the propagation of three-dimensional infrasonic waves, without using significant computational resources. By means of solving the obtained equation, the shapes of infrasonic signals recorded at distances of 295 km and 305 km from the explosion with energy of 30 kt THT were calculated. The observation point at the distance of 295 km (Tsimlyansk) was located in the western direction from the source. At this place, infrasonic signals were recorded corresponding to the sound propagation in the stratospheric and thermospheric acoustic waveguides. The presence of both two stratospheric and two thermospheric rays falling into the same observation point on the Earth's surface is a wave propagation feature result here. The recorded signals in Tsimlyansk also have a complex structure, both for stratospheric and thermospheric infrasonic arrivals. The registration point at a distance of 305 km (Saratov) was located north of the source. For this point, the calculations showed the presence of only thermospheric rays. The calculation results are compared with experimental data. A satisfactory agreement between the calculated and experimental data was obtained for both observation points in Saratov and Tsimlyansk. The calculated data in Tsimlyansk include manifestation features of the multipath structure of infrasound propagation and agree with the complex structure of infrasound signals recorded in Tsimlyansk.